The invention is concerned with the construction and manufacture of an inexpensive rotary switch of small size which has a high switching capability. Several factors contribute to the desired characteristics.
A principal feature is that each switch section has a rotor with annular conductive tracks thereon and four sets of stator contacts, two sets engaging each face of the rotor disc with one set on either side of the rotary shaft on which the disc is mounted. The positions of the contacts are staggered so that they engage alternate annular tracks on the rotor disc. The terminals of all of the contacts extend from a common planar edge of the switch section housing.
Another feature is that the switch section housing is made of two identical parts which may be molded of plastic and are preferably provided with complementary interengaging surfaces which hold the two parts together.
A further feature is that the stator contacts are mounted between ribs of each housing section with the lateral edges of the contacts having an interference fit with the walls of the ribs. More particularly, prongs extending from the lateral edges of the contacts engage the rib walls. Preferably sets of contacts, joined by a web, are assembled with the housing, e.g., pressed between the ribs, and then the web is severed. Guide channels in the rib walls receive the prongs.
Yet another feature is a detent mechanism having a disc with a serrated periphery, mounted on the switch shaft and balls held in engagement with the disc periphery by an arcuate spring that is free to move, distributing wear. The geometry of the serrations and balls affords a large number of angular positions in a small switch, with accurate angular position and crisp operation.
And a further feature is that the switch section (or multiple sections) is secured to the detent mechanism housing by a tie plate which extends through narrow slots in the lateral edges of the housing.